Flight recorder deployment mechanism

ABSTRACT

Embodiments of the invention are directed to a release device that uses an electro-mechanical mechanism instead of an explosive to deploy a deployable unit such as a flight data recorder. In one embodiment of the invention, a solenoid is activated that causes a piston surrounded by the solenoid to move which moves a pin attached to the piston and allows a spring to decompress and deploy a deployable unit. In some embodiments, a release actuator mechanism, a pneumatic actuator mechanism, a shape memory alloy or a combination thereof may be used to affect deployment of the deployable unit.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a non-provisional application of and claims thebenefit of priority of U.S. Provisional Application No. 61/785,511entitled “Flight Recorder Deployment Mechanism” filed on Mar. 14, 2013,which is herein incorporated by reference in its entirety for allpurposes.

BACKGROUND

In a catastrophic aviation event involving a downed aircraft, a flightrecorder is one of the most useful tools for investigators to piecetogether the crucial moments leading up to the aircraft accident orincident to determine the cause of the crash. One type of flightrecorder is a cockpit voice recorder (CVR) that records the audioenvironment of the flight deck of an aircraft. A CVR recordsconversations in the cockpit and communications between the cockpit crewand others such as air traffic control personnel on the ground. Anothertype of flight recorder is a flight data recorder that recordsinformation about the electronic and mechanical equipment of theaircraft. A flight data recorder records information such as flightparameters (e.g., altitude, speed, etc.) of the aircraft, and mayinclude engine performance data, or other information useful inassisting investigators to determine the cause of a crash.

A flight recorder is designed to withstand high impact forces and hightemperatures such that the flight recorder is likely to survive theconditions of a crash. However, while a flight recorder is designed tosurvive a crash, there is still a probability that the flight recordermay not survive if the crash conditions are extreme enough. Furthermore,a flight recorder is only useful if the flight recorder can be locatedafter a crash. For example, when an aircraft crashes at sea and issubmerged in water, locating the flight recorder affixed to the downedaircraft can take weeks to months, and even years, and can be costly interms of the amount of money and time spent in locating the flightrecorder. Even when an aircraft crashes on land, it may take significanteffort and time to locate the flight recorder, for example, when thecrash site is an unfamiliar or rough terrain. Such delay in locating theflight recorder not only frustrates investigators but can also risk thesafety of other aircrafts. For example, when a catastrophic aviationevent is caused by a design flaw in an aircraft component, the delay inidentifying the problematic component can risk the safety of otheraircrafts that employ the same type of aircraft component.

Flight recorders on aircraft collect at least 25 hours of flight dataand two hours of cockpit voice information. This information is storedwithin a crash-survivable memory module which can be retrieved in theevent of a crash or as part of regular maintenance. The Achilles' heelof typical “fixed” recorders is that they must be located in order toretrieve the data and in many cases cannot be found after a catastrophicincident. Deployable flight recorders solve this problem by separatingfrom the aircraft during a crash thereby avoiding the extreme conditionsof the impact zone and allowing for easier recovery.

Conventional deployable flight recorders rely on pyrotechnic or chemicalsystems to eject the flight recorder from the aircraft. Such systemsrequire use of explosive devices to trigger the deployment in the eventof a crash. For example, a low power explosive may be used to push theflight recorder off the aircraft. However, use of such systems can be asafety risk for installers and maintenance workers. Additionally, thepresence of explosive devices on the aircraft may cause a safety concernamong the passengers. In some cases, transportation regulations may notallow the use of explosive devices on an aircraft.

Embodiments of the invention address these and other problems,individually and collectively.

BRIEF SUMMARY

Embodiments of the invention are directed to devices and methods fordeploying a deployable unit without the use of an explosive. Embodimentsof the invention include a release device that utilizes anelectro-mechanical mechanism to deploy a deployable flight recorder froman aircraft in the event of a crash. As compared to conventionaldeployment systems that rely on explosive systems involving pyrotechnicsor chemicals, embodiments of the invention provide increased safetymargin for installers and maintenance workers, as well as an increase inthe operational safety of an aircraft due to the elimination ofexplosive devices from the aircraft.

In one embodiment of the invention, when a flight data recorder ismounted to a mounting tray on the aircraft, a spring is kept in acompressed state using a ball bearing interlocking mechanism. In theevent of a crash, an actuator may activate a piston to provide a pullingor pushing motion of a pin that is engaged with the ball bearings. Thisresults in the ball bearings to collapse into a channel, thus releasingthe spring. The spring extends from a compressed state and pushes theflight data recorder, thereby deploying it. The deployment or releasemechanism may be based on a solenoid, a release actuator mechanism, apneumatic actuator mechanism, a shape memory alloy or a combinationthereof that can be used to push or pull the pin.

One embodiment of the invention is directed to a release device for adeployable unit. The release device comprises a biasing element forinterfacing with the deployable unit and an electrical deviceoperationally coupled to the biasing element. The release device is freeof an explosive.

One embodiment of the invention is directed to a method for deploying adeployable unit. The method includes receiving an electrical activationsignal, by an electrical device, in response to an unexpected event. Inresponse to receiving the electrical activation signal, by theelectrical device, a biasing element interfacing with the deployableunit is activated to allow the biasing element to expand to an extendedconfiguration from a retracted configuration and deploy the deployableunit without the use of explosives.

These and other embodiments of the invention are described in furtherdetail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an automatic deployable flight recorder (ADFR) systemon an aircraft according to some embodiments.

FIG. 2 illustrates a block diagram of an ADFR system according to someembodiments.

FIG. 3A shows a deployable flight recorder assembly, according to someembodiments of the invention.

FIG. 3B shows a deployable flight recorder as it moves away from theaircraft structure, according to some embodiments of the invention.

FIG. 4 shows close up view of a release device, according to someembodiments of the invention.

FIG. 5A shows a cross sectional view of a release device, according tosome embodiments of the invention.

FIG. 5B shows a close up view of one end of the release device,according to some embodiments of the invention.

FIG. 5C shows a perspective view of an assembly including a releasedevice and a deployable flight recorder, according to some embodimentsof the invention.

FIG. 6A shows a cross sectional view of a release device interfacingwith a deployable flight recorder in an undeployed state, according tosome embodiments of the invention.

FIG. 6B shows a cross sectional view of a release device and adeployable flight recorder in a deployed state, according to someembodiments of the invention.

FIG. 7 shows a flow diagram for deploying a deployable unit, accordingto some embodiments of the invention.

DETAILED DESCRIPTION

Embodiments of the invention are directed to a release device thatemploys an electro-mechanical release mechanism without requiring theuse of pyrotechnics and/or explosives. In a catastrophic event or acrash, a deployable flight recorder is designed to disengage from theaircraft and move away from the aircraft body to improve recovery of theflight recorder after a crash. In some embodiments, the deployableflight recorder may be placed in the vertical tail fin of an aircraft orat other locations on the aircraft (e.g., on the airframe, one of thewings, etc.). A crash may be detected by using one or more crashdetection or deployment sensors. For example, an acceleration basedswitch may detect if the aircraft comes to a sudden stop or is in freefall, a frangible switch may detect deformation of the aircraft body, oran immersion sensor may detect if the aircraft is immersed or submergedin water.

In some embodiments of the invention, a release device may include abiasing element and an electrical device operationally coupled to thebiasing element. The biasing element may include any suitable devicewhich can assume an extended configuration and a retractedconfiguration. For example, in some embodiments, the biasing element mayinclude a spring or any other suitable compressible material that canexist in a compressed or extended configuration. In other embodiments,the biasing element may also include a pneumatic cylinder or othernon-explosive mechanical device that can assume an extended or retractedconfiguration.

The electrical device may include any suitable device that may receiveand provide an electrical signal. For example, in some embodiments, theelectrical device may include a solenoid, a switch, a relay, etc.

The release device may also include a piston within the solenoid and apin coupled to the piston. The pin can be at least partially surroundedby the biasing element. The release device may also include aninterlocking mechanism that may be used to hold the biasing element in acompressed state when a deployable flight recorder is mounted in amounting tray on an aircraft. When the crash detection sensors indicatea deployment criteria is satisfied (e.g., a crash or a potential crashis detected), an electrical activation signal may cause the interlockingmechanism to disengage, allowing the biasing element to expand and topush the deployable flight recorder into the air stream.

The electro-mechanical release mechanism according to embodiments of theinvention may be implemented using a solenoid, a release actuatormechanism, shape memory alloy or a pneumatic actuator mechanism usingcompressed air or non-explosive inert gas. As compared to conventionalrelease mechanisms involving pyrotechnics or chemicals that rely onthermal excitation with an inherent risk of causing fire, embodiments ofthe invention provide a safer, low maintenance and more reliablesolution over conventional release mechanisms.

FIG. 1 illustrates an automatic deployable flight recorder (ADFR) system100 on an aircraft 190. The ADFR system 100 may include a deployableflight recorder 130 on the vertical tail fin of aircraft 190 and crashsensors 122A, 124A, and 126A-D installed at various locations on theaircraft 190. The deployable flight recorder 130 may be designed todeploy and separate from aircraft 190 when the crash sensors 122A, 124A,and 126A-D working in a cooperative manner indicate that a deploymentcriteria (i.e. a deployment condition to initiate deployment ofdeployable flight recorder 130) is satisfied. The deployment criteria ofthe ADFR system 100 may change depending on the flight condition of theaircraft 190 such as when the aircraft is on the ground when theaircraft is taking off or landing, or when the aircraft is in flight ata cruising altitude or at a cruising speed.

In some embodiments, the deployable flight recorder 130 may beadvantageously installed near the leading edge of the root of thevertical tail fin of the aircraft 190 as shown in FIG. 1. Such alocation may allow the deployable flight recorder 130 to safely separatefrom an aircraft without impacting the body of the aircraft whendeployed during a crash under a variety of different flight conditionssuch as when the aircraft is climbing (e.g., during takeoff), descending(e.g., during landing), or in flight at a cruising altitude. Althoughthe location of the deployable flight recorder 130 as shown in FIG. 1 isoptimized to allow safe deployment from the aircraft 190, the deployableflight recorder 130 can alternatively be installed at other locations ofthe aircraft 190. For example, in other embodiments, the deployablefight recorder can be installed on other sections of the vertical tailfin, on the horizontal tail fin, on the airframe, or on either of thewings, etc.

The ADFR system 100 may include crash sensors that may be used tomeasure or monitor various physical parameters (e.g., water immersion,inertia including acceleration and/or deceleration, structuraldeformation, etc.) to detect conditions of a crash or conditions with ahigh likelihood of leading up to a crash, and may include variousdifferent types of crash sensors corresponding to the different types ofphysical parameters being measured or monitored. For example, the ADFRsystem 100 may include one or more immersion sensor(s) 122A, one or moreinertia sensor(s) 124A, and/or one or more structural sensor(s) 126A-D.The ADFR system 100 may also include other types of sensors such asimpact pressure sensors, acoustic crash sensors, and/or radar or opticalcrash sensors.

Immersion sensor(s) 122A may be used to detect submersion of an aircraftin a body of water. Immersions sensor(s) 122A may include submersionsensors and/or hydrostatic switches or immersion switches to detectsinking of an aircraft. Immersion sensors can be placed at strategiclocations on the aircraft to reliably detect the sinking of an aircraftand/or to differentiate between a safe water landing and a catastrophiccrash into a body of water. For example, immersion sensor 122A can beinstalled on the vertical tail fin of aircraft 190 as shown in FIG. 1,and in some embodiments, can be attached to a mounting tray that holdsthe deployable flight recorder 130 on the vertical tail fin.

Inertia sensor(s) 124A may be used to measure sudden changes in thevelocity (acceleration and/or deceleration) of an aircraft to detectmovement of the aircraft indicating a crash event.

Structural sensor(s) 126A-D may be used to detect deformation of thestructure of the aircraft such as deformation of the exterior shell ofthe aircraft or structural separation of sections of the aircraft.Structural sensors 126A-D can include frangible switches to detect acrash condition. Structural sensors 126A-D can be placed at strategiclocations on the aircraft at sections of the aircraft that are mostlikely to deform by impact forces.

In addition to the various types of crash sensors described above, theADFR system 100 in some embodiments may also include embedded aircraftsensors that may be used for maintenance and flight quality assurance.

FIG. 2 illustrates a block diagram of an ADFR system 200 in someembodiments of the invention. The ADFR system 200 may include a releasedevice 210 communicatively coupled to crash sensors 220, flight sensors240, and aircraft warning systems 250. The release device 210 may alsobe communicatively coupled to a deployable flight recorder 230, and maybe configured to activate deployment of the deployable flight datarecorder 230 from an aircraft when a deployment condition is detected(i.e. a deployment criteria is satisfied). In some embodiments, thedeployment criteria may depend on the flight condition of the aircraftas indicated by flight status information from flight sensors 240 and/ordanger warnings from aircraft warning systems 250.

The crash sensors 220 of the ADFR system 200 may include one or moreimmersion sensor(s) 122A, one or more inertia sensor(s) 124A, and/or oneor more structural sensor(s) 126A-D, as described with reference toFIG. 1. The crash sensors 220 may include one or more of other types ofcrash sensors such as an impact pressure sensor, an acoustic crashsensor, and/or a radar or optical crash sensor that are suitable fordetecting a crash condition. Crash sensors 220 may also include embeddedaircraft sensors as described above.

Flight sensors 240 may include sensors on the aircraft for measuringflight status information or flight parameters such as weight-on-wheels,speed (e.g., air speed and/or ground speed), acceleration, altitude,pitch, roll, engine speed, parking brake status, landing gear status,etc. In some embodiments, the flight status information from the flightsensors 240 can be used by the release device 210 to adjust thedeployment.

The aircraft warning systems 250 may be automatic safety systems of anaircraft that may alert the pilot of impending danger. The aircraftwarning systems 250 may include Master Caution/Warning Systems, GroundProximity Warning Systems, Collision Avoidance Systems, Stall WarningSystems, Power Loss Warning Systems, etc.

In some embodiments of the invention, the release device 210 may receivean electrical activation signal from one or more of the crash sensors220, flight sensors 240 and the aircraft warning systems 250 when adeployment criteria is satisfied. The release device 210 may enable thedeployment of the deployable flight recorder 230 based on the electricalactivation signal. For example, an electrical device in the releasedevice 210 may enable a biasing element interfacing with the deployableflight recorder 230 to expand based on an electro-mechanical mechanism,thus releasing the deployable flight recorder 230.

FIG. 3A shows a deployable flight recorder assembly 300 for a deployableflight recorder 302. The deployable flight recorder 302 may be similarto the deployable flight recorder 230 as shown in FIG. 2. The deployableflight recorder assembly 300 may include a mounting tray 304 that may beaffixed to the aircraft (e.g., aircraft 190) and may hold the deployableflight recorder 302 securely to the aircraft when the deployable flightrecorder 302 is in the undeployed state. When the deployable flightrecorder 302 is mounted to the mounting tray 304, the top surface of thedeployable flight recorder 302 may be flushed with the aircraft skin toreduce aerodynamic drag. The mounting tray 304 may comprise a rim 304B,which defines a cavity 304A. The cavity 304A may be cooperativelystructured with respect to the shape of the deployable flight recorder302. A release device 306 may also be present within the cavity 304A ofthe mounting tray 304. One end of the release device 306 may be attachedto the mounting tray 304 or may be attached to the underlying aircraftstructure through the base 304C of the mounting tray 304. The releasedevice 306 may be similar to the release device 210 as shown in FIG. 2and may be communicatively coupled to the crash sensors 220, flightsensors 240 and/or the aircraft warning systems 250.

The release device 306 may be configured to deploy the deployable flightrecorder 302, for example, when one or more crash sensors (e.g., crashsensors 220) detect a deployment criteria indicative of a crash or apotential crash, or when a pilot provides user input (e.g., pushes arelease button) to manually deploy the deployable flight recorder 302 incase of an emergency (e.g., aircraft warning systems 250). Whendeployed, the deployable flight recorder 302 is designed to move awayfrom the aircraft, and to separate from the aircraft without coming incontact with the aircraft structure after deployment. The base 304C ofthe mounting tray 204 may provide a cable connector 308 that can beconnected to a cable (not shown) to receive signals from aircraftelectronics and equipment. These signals may include an electricalactivation signal that may be used to control the deployment of thedeployable flight recorder 302, as well as other signals that are usedfor transmitting cockpit voice data and/or flight data to the deployableflight recorder 302 for recording. For example, the electricalactivation signal may be provided by the crash sensors 220, flightsensors 240 and/or the aircraft warning systems 250.

FIG. 3B shows deployable flight recorder 302 as it starts to move awayfrom an aircraft structure 312 (e.g., aircraft 190) during deployment,according to some embodiments. The deployable flight recorder 302, whichwas previously held in the cavity 304A of the mounting tray 304, isshown as separating from the mounting tray 304 and the aircraftstructure 312. When the deployable flight recorder 302 is deployed, aspring of the release device 306 may release or decompress in an outwarddirection away from the aircraft structure 312 to cause a front portionof the deployable flight recorder 302 to raise up from the aircraftstructure 312. The airstream 310 may push the front portion of thedeployable flight recorder 302 outward as a rear portion of thedeployable flight recorder 302 rotates in contact with a rear wall ofthe cavity 304A. This motion may allow the airstream to provide lift tothe deployable flight recorder 302 to enable the deployable flightrecorder 302 to safely separate from the aircraft structure 312.

FIG. 4 shows the release device 306 housed inside the mounting tray 304.In one embodiment, the release device 306 may comprise a spring 402 (inan extended configuration) coupled or attached to a base member 404 thatis secured to a mounting plate 406. The mounting plate 406 may beaffixed to the inner surface of the cavity 304A. In other embodiments,the release device 306 can be affixed directly to the body of theaircraft 190 through a hole or void in the mounting tray 304. It will beunderstood that other mechanisms to couple the release device 306 to theaircraft 190 are possible.

FIG. 5A shows a cross section view of a release device 500 that can beused to deploy a deployable unit, according to some embodiments of theinvention. For example, the release device 500 may be used to deploy thedeployable flight recorder 302 as shown in FIGS. 3A and 3B. In oneembodiment, the release device 500 may be installed inside the cavity304A of the mounting tray 304. The release device 500 may include abiasing element 514, a pin 502 at least partially within the biasingelement 514, a piston 506 coupled to the pin 502, a solenoid 508 aroundthe piston 506, and one or more ball bearings 504 engaged with the pin502. The release device 500 may also include a body 540 that may includeone or more separable components. In this example, the body 540 includesa rubber bushing 520 at a front region of the release device 500, a pinhousing 524 in contact with the rubber busing 520, an actuator housing526 coupled to the pin housing 524, a bushing 528 at a rear region ofthe release device 500 and proximate to the actuator housing 526, and aconnector assembly 530 at the rear region of the release device 500 andbeing electrically and mechanically coupled to the solenoid 508.Different parts of the body 540 may include same or different materialsuch as rubber, plastic, metal, etc.

The release device 500 may be configured to interface with a deployableunit 538 by engaging with one or more catches 516 on the deployable unit538.

The biasing element 514 may include a spring or a compressible material.The biasing element 514 may be external to the body 540 of the releasedevice 500 and may be exposed. One end of the biasing element 514 may beattached to the body 540 of the release device 500. In otherembodiments, the biasing element 514 may be freestanding and is pushedagainst the body 540 of the release device 500 by the deployable unit538 that may be installed in the cavity 304A of the mounting tray 304.The biasing element 514 may be configured to at least partially surroundthe pin 502 that may be housed in the pin housing 524, when the biasingelement 514 is compressed or extended.

The pin housing 524 may house the pin 502 and define a channel 512 inwhich the pin 502 can move. For example, the channel 512 may be part ofa hollow passage along an axis of the pin housing 524. In someembodiments, the hollow passage may include appropriate dimensions toaccommodate various ridges and grooves on the pin 502. According to someembodiments, the pin 502 may be allowed to move along the length of thechannel 512 (e.g., horizontally as shown in the perspective of FIG. 5).In other embodiments, the channel 512 may be defined to allow the pin502 to move in other directions.

The pin 502 may include a set of one or more ridges (or bearingshoulders/surfaces) 522 and a set of one or more grooves 518. A firstend 532 of the pin 502 may be flat or may be elongated. In someembodiments, each ridge in the set of ridges 522 near the first end 532of the pin 502 may be designed to push against a ball bearing 504 tokeep the biasing element 514 in the compressed state.

A second end 534 of the pin 502 may be coupled to the piston 506. Forexample, the second end 534 of the pin 502 may be attached to the piston506 or may be screwed into a front end the piston 506. The pin 502 mayinclude appropriate dimensions to allow the pin 502 to be able to movefreely within the channel 512. The pin 502 may comprise a rigid materialsuch as stainless steel 17-4PH. Note that the design of the pin 502, asshown in FIG. 5A, corresponds to one embodiment, but other suitabledesigns of the pin 502 are possible. In some embodiments, the first end532 of the pin 502 may be used to set off a switch in the flight datarecorder (not shown in FIG. 5A) when the biasing element 514 isreleased. The switch may be a switch that activates a device in theflight data recorder such as a signal such as light, homing beacon, etc.

The piston 506 may be configured to move freely within the solenoid 508.In some embodiments, the piston 506 may also be referred to as a coreand may comprise a magnetic material such as iron. The piston 506 mayinclude a cylindrical, rectangular or any suitable shape that may allowthe piston 506 to move along an axis within the solenoid 508. In someembodiments, the force generated by the solenoid 508 may depend upon thematerial and shape of the piston 506.

The solenoid 508 may include electromagnetically inductive coil. Thesolenoid may be configured to convert electrical energy into linearmotion when activated by an electrical activation signal. For example,when an electrical activation signal 537 in a wire 536 is received bythe release device 500, the solenoid 508 may generate a magnetic fieldthat may cause the piston 506 (or core) within the solenoid 508 to move.In some embodiments, dimensions of the solenoid 508 may determine theappropriate force required to deploy the deployable unit 538. Dimensionsof the solenoid may include length of the coil, number of turns in thecoil, thickness of the coil, etc. For example, the dimensions of thesolenoid 508 may determine the magnetic field generated by the solenoid508 to move the piston 506 which moves the pin 502 resulting in releaseof the biasing element 514. In some embodiments, the force generated bythe solenoid 508 may also depend upon the material of the coil and thewinding of the coil. In some embodiments, the force generated by thesolenoid 508 in order to deploy a deployable flight recorder may be inthe range of 40-60 pounds.

The pin housing 524 may also include a set of one or more openings orapertures 542 in a collar 544 of the release device 500, as shown inFIG. 5B. The ball bearings 504 engage with the catch 516 on thedeployable unit 538 to hold the biasing element 514 in a compressedstate. When the release device 500 is in the unreleased or undeployedstate, the pin 502 is held in a position in which one or more of ridges522 on the pin 502 push against the ball bearings 504 radially outwardfrom the channel 512 such that ball bearings 504 partially protrude outof the collar 544 through the openings 542. The openings 542 can beshaped to prevent the ball bearings 504 from being pushed out throughthe openings 542. For example, each of the openings 542 may be acircular opening with a radius that is smaller than the radius of theball bearing 504. In this manner, ball bearings 504 cannot fall out ofthe openings 542, and the ball bearings 504 can be retained with therelease device 500.

FIG. 5C illustrates an exemplary embodiment of the deployable unit 538with the catch 516. The catch 516 can be a latch, a socket, a clip, aclasp, or other mechanical structure that snugly mates with the exposedportions of the ball bearings 504. For example, the catch 516 may have aset of one or more depressions, grooves, or cavities having asemi-spherical shape that is cooperatively structured with the shape ofthe exposed portions of ball bearings 504 such that the catch 516 cangrip onto and interlock with the ball bearings 504. In some embodiments,the catch 516 may be provided as part of the housing of the deployableunit 538 such that when the deployable unit 538 is installed in amounting tray 546, the deployable unit 538 pushes against the biasingelement 514, and the catch 516 on the housing of the deployable unit 538interlocks with the ball bearings 504 to keep the biasing element 514compressed. In other embodiments, the catch 516 can be provided as partof the mounting tray 546 or part of the release device 500 such that thebiasing element 514 can be kept in a compressed state independently ofwhether a deployable unit 538 is installed in the mounting tray 546.

Referring back to FIG. 5A, movement of the pin 502 in the channel 512may be controlled by the solenoid 508. When the solenoid 508 isactivated, the piston 506 coupled to pin 502 can push or pull the pin502 along the length of the channel 512. The solenoid 508 may beactivated by an electrical activation signal 537 when a crash event isdetected to deploy the deployable unit 538. The electrical activationsignal 537 may provide an electrical current to the solenoid 508 to movethe piston 506 forward towards the biasing element 514 or backwardstowards the right side from the perspective of FIG. 5A. In someembodiments, the electrical activation signal 537 may be providedthrough the cable connector 308 as shown with reference to FIG. 3A.

The pushing or pulling motion of the piston 506 may cause the pin 502 tomove axially within the channel 512. Movement of the pin 502 may causethe ridges 522 on the pin 502 to slide against the ball bearings 504until the ridges 522 disengage with the ball bearings 504. When movementof the pin 504 aligns the grooves 518 with the openings 542 as the pin502 is being pushed forward or pulled backward, the space provided bythe grooves 518 in the channel 512 allows the ball bearings 504 to fallor collapse into the channel 512. When the ball bearings 504 collapseinto the channel 512, the ball bearings 504 no longer protrude out ofthe openings 542. As a result, the catch 516 used to hold the biasingelement 514 in the compressed state is no longer interlocked with theball bearings 504. This releases the biasing element 514 into anuncompressed state, pushing the deployable unit 538 outward from themounting tray 546, and hence deploying the deployable unit 538 from theaircraft.

In other embodiments, instead of using spherical ball bearings as theinterlocking mechanism, other shapes can be used. For example, atrapezoidal spacer can be used. A trapezoid shaped spacer may allow thespacer to protrude out from the opening of the pin housing withoutfalling out of the pin housing. The trapezoid shaped spacer cansimilarly collapse into the channel of the pin housing using thetechniques described above to affect deployment of the deployable unit.In other embodiments, other latching mechanism that can be released bythe movement of a pin can be used.

In some embodiments, the release device 500 may include a pneumaticactuator device coupled to the solenoid 508. For example, the solenoid508 may be used as a valve, a relay or a switch which may be activatedby the electrical activation signal 537. The pneumatic actuator mayutilize a compressed air or a non-explosive inert gas pressure system tomove the piston 506 when enabled by the solenoid 508. For example, astandard air hose nipple may be provisioned by the electrical activationsignal 537 to change the pressure of the compressed air or thenon-explosive inert gas to move the piston 506. In some embodiments, thepneumatic actuator and the solenoid 508 may be housed inside theactuator housing 526.

In some embodiments, the release device 500 may include a releaseactuator device coupled to the solenoid 508. For example, the releaseactuator device may utilize a linear, rotary or any other suitablerelease actuator to move the piston 506 when the current is supplied tothe solenoid 508.

In some embodiments, a shape memory alloy may be used to engage thecatch to hold the biasing element 514 in a compressed state. Shapememory alloys are metals that can change their shape in response to anelectrical or magnetic charge. Some common examples of shape memoryalloys include Nickel-Titanium, Copper-Aluminum-Nickel andCopper-Zinc-Aluminum. In the inert state, the shape memory alloymaintains one shape, and when a sufficient electric or magnetic chargeis applied, the shape memory alloy changes to a different shape. Forexample, the shape memory alloy may be shaped like a hook in the inertstate. The hook portion can protrude out of a housing to engage with thecatch 516 when the release device 500 is in the unreleased or undeployedstate. When the electrical activation signal 537 is applied to the shapememory alloy, the shape memory alloy can straighten out to disengage thecatch 516, and thus releasing the biasing element 514 to deploy thedeployable unit 538. In other embodiments, the biasing element 514 maycomprise a shape memory alloy. The shape memory alloy may be in the formof a coil spring that expands upon the application of current.

FIG. 6A illustrates a cross section view of a release device engagedwith a deployable unit.

An assembly 600 may include the release device 500 and the deployableunit 538. As illustrated in the figure, the deployable unit 538 is in anundeployed state. The ridges 522 of the pin 502 engage with and pushagainst the ball bearings 504 to force the ball bearings 504 topartially protrude out of the openings 542, as shown in FIG. 5B. Thecatch 516 interlocks with the exposed portions of the ball bearings 504to keep the biasing element 514 compressed. The catch 516 can be part ofthe housing of the deployable unit 538, or part of a mounting tray towhich deployable unit 538 may be mounted or part of the release device500.

FIG. 6B shows the deployable unit 538 in the released or deployed state.An electrical activation signal indicating the detection of a crash orpotential crash can activate the solenoid 508. The magnetic fieldgenerated by the solenoid 508 moves the piston 506 to cause the pin 502to push forward towards the biasing element 514. Alternatively, the pin502 can be pulled backwards away from the biasing element 514. This mayallow the ball bearings 504 to roll around the ridges 522 and collapseinto the channel 512. In some embodiments, the movement of the pin 502may cause the openings in the pin housing 524 to align with the grooves518. Once the ball bearings 504 fall into the channel 512, the catch 516is no longer engaged with the ball bearings 504. As a result, thebiasing element 514 is released into a decompressed state to push thedeployable unit 538 off the mounting tray, and hence deploying thedeployable unit 538 from the aircraft. In some embodiments, theactuation time to deploy the deployable unit may be in the order of 8milliseconds after the electrical activation signal is received.

FIG. 7 shows a flow diagram for a method to deploy a deployable unitinterfacing with a release unit, in accordance with some embodiments ofthe invention.

In step 702, an electrical activation signal is received by an electricdevice in response to an unexpected event. For example, the electricalactivation signal 537 may be received by the release device 500 from oneof the sensors in the event of a crash, as described with reference toFIG. 2. The electrical activation signal 537 may be received in the wire536 via the cable connector 308 as shown in FIG. 3A.

In step 704, a piston operationally coupled to the electrical device ismoved. Referring back to FIG. 6B, the electrical activation signal 537may be used to provide current to the solenoid 508 to activate thesolenoid 508. Applying current to the solenoid 508 may generate amagnetic field which can move the piston 506 within the solenoid 508.

In step 706, a pin coupled to the piston is moved. Movement of thepiston 506 may cause the pin 502 coupled to the piston 506 to move. Forexample, the pin 502 may move within the channel 512 in the pin housing524.

In step 708, one or more ball bearings engaged with the pin arewithdrawn from apertures in a housing and a catch in the deployableunit. For example, moving the pin 502 may cause the ball bearings 504engaged with the pin 502 to withdraw from the openings 542 in thehousing 524 and the catch 516 in the deployable unit 538.

In step 710, a biasing element interfacing with the deployable unit isallowed to expand to an extended configuration from a retractedconfiguration. As discussed previously with reference to FIG. 6A, priorto receiving the activation signal 537 in the wire 536, the deployableunit 538 may be engaged with the release unit 500 (e.g., by the catch516) keeping the biasing element 514 compressed. Referring back to FIG.6B, the biasing element 514 may be expanded when the ball bearings 504are withdrawn due to the movement of the pin 502. In some embodiments, ashape memory alloy may be used to release the biasing element 514, asdescribed previously.

In step 712, the deployable unit interfacing with the biasing element isdeployed or released without the use of explosives. Referring back toFIG. 6B, release of the biasing element 514 may cause the catch 516 onthe deployable unit 538 to disengage from the release unit 500 anddeploy the deployable unit 538 to move away from the aircraft body.

In embodiments of the invention, deployment of a deployable unit can beaccomplished using electro-mechanical means, instead of the conventionalmethods of using pyrotechnics or chemical reactions. For example, theconventional release devices may use gun powder or black powder toignite using a squib and move the piston with a small explosion. Thus,embodiments of the invention can provide an increased safety margin forinstallers and maintenance workers. Additionally, it can provide anincrease in the operational safety of an aircraft due to the eliminationof explosive devices from the aircraft. Note that the embodiments of theinvention are not limited to flight data recorders and may be used infuel tanks, stores, doors, hatches, ramps, etc. where anelectro-mechanical mechanism may be used.

The above description is illustrative and is not restrictive. Manyvariations of the invention will become apparent to those skilled in theart upon review of the disclosure. The scope of the invention should,therefore, be determined not with reference to the above description,but instead should be determined with reference to the pending claimsalong with their full scope or equivalents.

One or more features from any embodiment may be combined with one ormore features of any other embodiment without departing from the scopeof the invention.

A recitation of “a”, “an” or “the” is intended to mean “one or more”unless specifically indicated to the contrary.

It should be understood that the present invention as described abovecan be implemented in the form of control logic using computer softwarein a modular or integrated manner. Based on the disclosure and teachingsprovided herein, a person of ordinary skill in the art will know andappreciate other ways and/or methods to implement the present inventionusing hardware and a combination of hardware and software.

1. A release device for a deployable unit, the release devicecomprising: a biasing element for interfacing with the deployable unit;and an electrical device operationally coupled to the biasing element,wherein the release device is free of an explosive.
 2. The releasedevice of claim 1, wherein the deployable unit is a deployable flightrecorder, the biasing element is a spring and the electrical devicecomprises a solenoid, and wherein the release device further comprises:a piston within the solenoid; and a pin coupled to the piston, whereinthe pin is at least partially surrounded by the spring.
 3. (canceled) 4.The release device of claim 2, wherein the release device furthercomprises a housing comprising a channel which receives the pin. 5.(canceled)
 6. The release device of claim 2, further comprising a wirecoupled to the solenoid, wherein the wire is configured to receive anelectrical activation signal.
 7. The release device of claim 1, whereinthe release device comprises a shape memory alloy.
 8. The release deviceof claim 1 wherein the electrical device comprises an electrical switch.9. The release device of claim 1, wherein the biasing element comprisesa pneumatic actuator device coupled to the electrical device.
 10. Therelease device of claim 9, wherein the pneumatic actuator devicecomprises a compressed air device.
 11. The release device of claim 9,wherein the pneumatic actuator device comprises an inert gas device. 12.The release device of claim 1, wherein the electrical device comprises asolenoid, a switch or a relay.
 13. The release device of claim 1 whereinthe biasing element is a spring.
 14. An assembly comprising: the releasedevice of claim 1; and the deployable unit.
 15. A system comprising theassembly of claim 14; and an aircraft coupled to the assembly.
 16. Amethod for deploying a deployable unit, the method comprising: receivingan electrical activation signal, by an electrical device, in response toan unexpected event; and in response to receiving the electricalactivation signal, by the electrical device, activating a biasingelement interfacing with the deployable unit to allow the biasingelement to expand to an extended configuration from a retractedconfiguration and deploy the deployable unit without the use ofexplosives.
 17. The method of claim 16, further comprising: prior toreceiving the electrical activation signal, compressing the biasingelement to keep the deployable unit in an undeployed state. 18.(canceled)
 19. The method of claim 16, wherein the electrical device isa solenoid, the biasing element is a spring and the deployable unit is adeployable flight recorder.
 20. The method of claim 16, wherein thebiasing element comprises a shape memory alloy.